Ditto to what Cole said. I have in my computer bag a boot disk (image on laptop...) from years ago (like '99 or so I think...) that every once and a while still I need to run-if the box has a floppy or use usb floppy..... For the life of me I do not know the name of the thing, but it is basically a Linux boot floppy that edits the Win XP hive files...

I had a similar problem and found a program to delete the password on my machine. The program was "Offline NT Password & Registry Editor password cracker" (very descriptive name, yes?). If you email me with your address I can send the zip file (3.5MB). I copied it onto flash drive and booted from it. Easy Peasy.

ONE WARNING: Whenever you delete a password, you must accept the risk of damaging a link that would have used that password. In othe words, your backup software used that password or software that uses the admin password for access, will not work. This should be easily fixed by updating the password.. I did not experience any problems and believe that it would only happen under certain conditions, but you just need to be aware...

I used to have some very handy software that booted into Linux then did a screen report of every password on the computer, so you could just note down the passwords and then logon as admin again, but for the life of me i cant find it!

I've actually used ophcrack a lot. My girlfriends Mother routinely loses her password, and doesn't like multiple accounts so I've just avoided setting up an admin account. Ophcrack seems to work reliably enough that it hasn't been an issue.